Apparatus and method for continuous filtering

ABSTRACT

A traveling filter comprising a plurality of trays disposed to travel along a path, a plurality of frames adapted to travel along a second path and through a portion of said path mate with the trays to confine material thereon, and a plurality of conduit means adapted to travel along a third path and adapted to be advanced and retracted to establish communication with and discharge liquid from said trays.

Unlted States Patent 1 1 1111 3,791,521 Eakins 1 Feb. 12, 1974 [54]APPARATUS AND METHOD FOR 3,138,088 6/1964 Foth 210/77 x CONTINUOUSFILTERING [76] Inventor: William S. Eakins, St. Andrews Ln.,

Glen Cove 11542 Primary ExaminerJohn Adee Attorney, Agent, orFirm-Kenyon & Kenyon Reilly [22] Filed: July 8, 19,71 Carr & Chapin [2]]Appl. No.: 160,746

Related US. Application Data Continuation-in-part of Ser. No. 845,984,July 30, 1969, Pat. No. 3,615,011, Continuation-impart of Ser/No.613,691, Dec. 21, 1966, Pat. No. 3,460,674,

and a continuation-in-part of Ser. No. 578,361, Sept. 9, 1966,abandoned.

U.S. c1. 210/67, 210/393 1m. 01 B0ld 33/04 Field of Search 210/67, 391,77, 328, 332,

References Cited UNITED STATES PATENTS 4/1963 Bounin 210/77 X 5 7ABSTRACT A traveling filter comprising a: plurality of trays disposed totravel along a path, a plurality of frames adapted to travel along asecond path and through a portion of said path mate with the trays toconfine material thereon, and a plurality of conduit means adapted totravel along a third path and adapted to be advanced and retracted toestablish communication with and discharge liquid from said trays.

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PATENTEU FEB 12 1914 SHEET 170F W I N VEN TOR. Mum/1y S (Lyn V wwwzw NowVa i 1 APPARATUS AND FOR CONTINUOUS FILTERING This application is acontinuation-in part of my copending application Sen No. 845,984 filedJuly 30, 1969, now US. Pat. No. 3,61'5,01l, issued Oct. 26, 1971,application Ser. No. 845,984 being a division of my then copendingapplication filed Dec. 21, 1966 which issued as U.S. Pat. No.3,460,674,the last menwhether it be induced by a pressure or a vacuumsource, to 'thetr'aveling filter inorder to'treat the filter cake beingaccumulated upon the filter medium. During and after the deliveryof thematerial to be filtered to the'filter-medium which can'be'mountd upon a'filter tray, it isgenerally necessary to apply a vacuum conditionin'orderto'draw the liquid portion o f the'material through the filtermedium and thereby separate and buildup a filter cake upon the medium.Since filtering apparatus commonlyemploys an'endless' beltof-appreciable length ofa plurality'of traveling filt'er trays and sinceitis u'suallynecessary to apply 'a'v'acuum or pressure condition*to thebelt-or trays'over-an'eiitensive-period of travel, it"becornes difficultto provide the necessary equipment for subjecting the belt-oreach of thefilter trays at least through Zpar t of their travel throughout theapparatus 'toa vacuum or .pressure condition without involving undue Icomplexity or shortened life forthe equipment.

1n the prior art, vacuum has been applied to an endless belt or to 'theseparate trays of atravelingfilterby providing an'elongatedsuction-boxover whichthebelt or trays are advanced. Since hisnecessary-toforma seal between the bottom portion of l the belt orthetrays and the suctionbox, the resulting arrangement'is generally subject:to excessive leakage and a comparatively high rate of wear'between thefixed and stationary portions of the seal.

Another difficulty encountered with traveling filters has been that ofobtaining an efficient, reliable and-durable arrangementfor removingthefilter cake after'its formationupon the filter medium. Whereverap'lurality of continuously moving 'trays each having a-filt'er'mediumare employed,difficultyis experienced in removingthe filter cake fromthe'tray sincethe caketends to cling firmly to'the tray and tothe'filtermedium even though the tray is inverted after the formation ofthe filter cake. Where'eachtray'is providedwith side walls ofsufficient'height to receiveand confine-a substantial quantity ofmaterial-to befiltered, the'side walls'ofthe tray present a greaterarea'to *whichthefilter-cake can cling and adhere during attemptstoremove'the cake from the tray. Attempts to insure removal of thecakefrom the tray by the applicationof'reverse'blasts' or jets of pressurefluid tothe filter cake have alsore'sulted in complicated designs whichstill I fail 'to provide for the simple and'reliable removalo'fthefilter'cake from "the filter medium withinthe tray.

It is therefore one of the objects'of the invention to provide atraveling filter to which flow of pressure or vacuum fluid can beapplied without the need of continuously sliding seals or the likebetween the filter trays and the source of the fiow of pressured orvacuum fluid.

It is another object of the invention to provide a traveling filter inwhich the duration of the applying of pressure or vacuum to the filtertrays-can be accurately controlled.

It is still another objectof the invention to provide a traveling filterin which pressure or vacuumcan be applied in a controlled manner withrespect to each of the filter trays independently'of one another.

It is an additional object of the invention to provide atraveling'filterin'which fluid can be applied with respect to each tray individually'even'though the filter travels over an appreciable distance.

It is a furthe'r object of the invention to provide a trevelingfilter=in which the construction of the trays is conditioned tofacilitate the release and'theremoval of feed 'thetraysofatravlingfilter insequential-manner.

Itis another object of the invention to provide a traveling filter inwhich the filter medium of each of the trays can be operated-tofacilitate the 'removalofthe filter cake therefrom. I

Inone of the-embodiments of f the invention the traveling filterincludes 'a plurality of tray members each having afilter medium'whichis-adated toreceive material tobefilteredi'Each ofthe'pluralityoftraymembers has a passage for passing a' flow' of fluid =with respect'to the-tray member. 'Means are provided "for conveying the plurality of traymembers along a predetermined path. Atleas't one-conduita'dapted tobeconnected to a device for'producing a flowof 'fiuid' is:provided. Inaddition, means are :provided for driving the conduit alonganadditional-path adjacent'to-at least-a portion of the predeterminedpathof thetray membersMeans are also provided -for successively advancingand re- 'tracting'the-conduit with r'espec't'to its additional pathas'the conduit'is driven in order suceessively 't o-enage and-disenagethe conduit with respect to the passage' of the 'tray member as "thetray member I is conveyed.

An'advantage-of this arrangement is'thatthe operation of theconduit'canbe'conveniently'established at various locations alongthepredetermined path;of the tray-member since the conduit isdrivenadjacentto the path of "the tray members'and sincethe conduit isadvanced and-retracted with respect'to its own path. An additionaladvantageisthat it enablesa'flow of fluid to be controlledwith'rsp'ectto each'individual tray member independently of theremaining'traymembers. Another advantageis that-the 'advancing'an'd retracting ofthe conduit enables th'epassa'ge' of thetraymember'to be eng'agedanddisengaged at various locations along 'its predetermined path or'travel'without interfering with theconveying of the-tray member.

In another embodiment of the invention the tray members are providedwith a cavity with whichthe passage is in communication and over whichthe filter medium is disposed. This construction enables the conduit toestablish a flow of fluid with respect to the filter medium by way ofthe cavity.

In still another embodiment of the invention the filter medium of eachof the plurality of tray members extends in a substantially horizontalplane throughout at least a portion of the predetermined path of thetray members in order to assist the accumulation of a filter cake uponthe filter medium.

In an additional embodiment of the invention the conduit compries atubular member which is adapted to successively engage and disengage thepassage of the tray member in order to establish a flow of fluid withrespect to the tray member.

In a further embodiment of the invention the traveling filter comprisesa plurality of tray members each having a filter medium and means forconveying the tray members along a predetermined path. The filterfurther includes a plurality of frame members each having an openingadapted to mate in a facing relationship with the surface area of thefilter medium. Means are provided for moving the plurality of framemembers along another path extending at least in part adjacent to thepredetermined path of the tray members in order successively to placeand remove the opening of each of a portion of the plurality of framemembers with respect to a conidtion of registry and substantialengagement with a different one of the tray members of a correspondingportion of the plurality of tray members.

An advantage of this arrangement is that the frame members are adaptedto confine the material to be filtered upon the filter medium adjacentthereto. Subsequently, upon removal of the frame members from inregistry and substantial engagement with the tray members, the removalof the filter cakes from the filter mediums is facilitated and made morepositive.

In still a further embodiment of the invention the conveying means forthe pluraity of tray members and the plurality of frame members eachhave upper and lower reaches with at least a portion of the lower reachof the frame members overlying and sufficiently adjacent to the upperreach of the tray members in order to enable the frame members to beplaced in registry and substantial engagement with the tray'members.

In another embodiment of the invention the traveling filter includesmeans for delivering the material to be filtered through the openings ofthe frame members as .the frame members are moved along the lower reachof their conveying means.

In another embodiment, a hopper is positioned within the reach of theconveying means to be filled with feed material and intermittentlypivotedin response to the presence of atray underneath to dump itscontents into successive trays.

In a still further embodiment of the invention, the traveling filter hasa take-up roller mounted adjacent a conveying means and a pair ofscrapper blades. The take-up roller is provided with ports in thesurface which communicate with a vacuum source to hold the cake materialand the blades are arranged so that one scrapes a filter cake onto theroller and the other scrapes an upper layer of cake material from theroller at an advanced position.

Various other objects and advantages of the present invention will bereadily apparent from the following detailed description when consideredin connection with the accompanying drawings in which:

FIG. 1 is an elevational view of the traveling filter of the inventionshowing the lower reach of the conveyor of the frame members overlyingand in substantial engagement with the upper reach of the conveyor ofthe tray members with means for successively advancing and retractingthe conduits disposed adjacent to the upper reach of the conveyor forthe tray members;

FIG. 2 is a fragmentary elevational view of the traveling filter showingthe means for driving the conduits along an additional path adjacent toa portion of the predetermined path of the tray members;

FIG. 3 is a fragmentary plan view of the conveyor for the tray membersshowing the conduits and the means for driving the conduits along anadditional path adjacent to a portion of the predetermined path of theconveyor of the tray members;

FIG. 4 is a plan view of a single one of the assemblies of conduits withthe means for successively advancing and retracting the conduits as theyare driven with respect to the conveyor for the tray members;

FIG. 5 is a vertical section view taken along the line 5-5 in FIG. 4 andshowing the control valve arrangement for the flow of fluid through theconduits;

FIG. 6 is a vertical section view taken along the line 6-6 of FIG. 5 andshowing the means for driving the conduits along an additional pathadacent to the predetermined path of the tray members;

FIG. 7 is a perspective view of one of the plurality of tray members andone of the plurality of frame members in registry and substantiallyengaged with the tray member;

FIG. 8 is a vertical section view taken along a plane extending parallelto the line of travel of the tray membr and showing the cavity, thefilter medium and the passage of the tray member;

FIG. 9 is a plan view of one of the tray members showing the filtermedium overlying the plate of the tray member;

FIG. 10 is an elevational view of the end portion of a passage connectedto a tray member showing the alternate titled portions which the passagecan assume with respect to its support;

FIG. 11 is a vertical section view taken along the line 1l11 in FIG.8'and showing the passage and the valve connected thereto for a traymember in alignment with the conduit;

FIG. 12 is a fragmentary vertical section view showing the opening of aconduit advancing into engagement with the valve of the passage leadingto the tray member;

FIG. 13 is a fragmentary vertical section view showing the opening ofthe conduit fully engaged with the open valve of the passage leading tothe tray member;

FIG. 14 is a fragmentary vertical section view of the conveyors for theframe members and the tray members and showing the filter cake beingreleased from the tray member after removal of the frame member;

FIG. 15 is a fragmentary vertical section view showing a detachablefilter medium for facilitating the removal of the filter cake;

FIG. 16 is a fragmentary vertical section-view showing means forassisting in the removal of the filter cake from the detachable filtermedium;

2. An apparatus in accordance with claim 1 and further comprising an additional scraper blade disposed adjacent to the surface of said filter downstream of said roller, said additional scraper blade extending adjacent to the periphery of said roller and to a substantially close clearance with respect to the surface of said filter medium, whereby said additional scraper blade assists in the removal of the filter cake therefrom.
 3. An apparatus in accordance with claim 1 and further comprising means for pivotally mounting said porous roller and said scraper, means for biasing said mounting means toward said filter medium, and means for engaging said mounting means to limit the clearance between said roller and said filter medium.
 4. An apparatus in accordAnce with claim 1 in which said roller has end portions which extend axially beyond said additional filter medium on said roller and which have a slightly larger outside diameter than said additional filter medium, said end portions being adapted to engage said filter medium and said scraper blade establish a predetermined clearance between said filter medium and said additional filter medium and between said scraper blade and said additional filter medium.
 5. Method of removing filter cake from the filter medium of a moving filter comprising positioning a porous roller having an additional filter medium disposed thereupon adjacent the path of travel of the filter medium of the moving filter and at a substantially close clearance therewith, rotating the roller with the peripheral movement thereof being in the same direction as the movement of the filter medium of the moving filter, inducing fluid flow through the additional filter medium into the porous roller, the fluid flow forming an additional filter cake upon the roller from the filter cake on the filter medium, the additional filter cake engaging the filter cake on the filter medium, and scraping a layer of filtered material from the roller to retain a uniform layer of additional filter cake thereon and to remove the remainder of filtered material therefrom, whereby the engagement of the additional filter cake on the roller with the filter cake on the filter medium enables the filter cake on the filter medium to be removed.
 6. A method in accordance with claim 5 and further comprising the step of scraping the filter cake from the filter medium downstream of the roller and adjacent thereto. 